Bioactive chemical constituents from Hyptis suaveolens stem

Our previous studies have found that the aerial part of Hyptis rhomboides and the seed of Hyptis suaveolens contain xanthine oxidase (XO) inhibitors, inspiring us to investigate the chemical constituents of H. suaveolens stem. The EtOH extract of H. suaveolens stem was fractionated by liquid-liquid partitioning, followed by separation over Sephadex LH-20, silica gel, and reverse-phase column chromatography, centrifugal partition chromatography, and semipreparative RP-HPLC, to give 17 bioactive isolates. Of these, dimethyl melitrate A (9) is a new natural product, 10 is likely (700 E)-90 -methyl melitrate A, only caffeic acid (2) is the same as those isolated from the seed of the same plant, and only nepetoidins A (14) and B (11) are the same as those from H. rhomboides stem. Nepetoidin B (11) showed the best anti-XO activity. Rosmarinic acid (3) is the most abundant (>661 ppm; w/w, dried stem), while melitric acid (12) (>277 ppm), caffeic acid (2; >125 ppm), and methyl rosmarinate (4; >81 ppm) are the major ones. This outcome could serve as a good basis for chemotaxonomy of the Hyptis plants and is beneficial for developing H. suaveolens stem as anti-hyperuricemic nutraceutical.